Cyclobenzaprine Hydrochloride, a skeletal muscle relaxant is currently available as immediate release tablets containing 5 mg or 10 mg of the active and also as extended release capsules containing 15 mg or 30 mg of the active. Immediate release tablets are recommended to be administered three times a day to achieve relief from muscle spasm. Administration of such tablets three times a day is a major compliance issue especially in elderly patients. To substantially enhance patient compliance, it is desirable to provide cyclobenzaprine hydrochloride in extended release dosage form for once a day administration.
U.S. Pat. No. 7,387,793, U.S. Pat. No. 7,544,372, US Patent Application 2008/0124398, US Patent Application 2009/0017126, US Patent Application 2009/0017127 and US Patent Application 20090148532 disclose multi-particulate pharmaceutical dosage forms of a skeletal muscle relaxant for once a day administration comprising a population of extended release beads. These extended release beads comprise:                an active-containing core particle comprising a skeletal muscle relaxant selected from the group consisting of cyclobenzaprine, pharmaceutically acceptable salts or derivatives thereof and mixtures thereof; and        an extended release coating comprising a water insoluble polymer membrane surrounding the said core, wherein the membrane comprises a water insoluble polymer and a plasticizer.        
The dosage form exhibits the following in-vitro dissolution profile in USP apparatus 2 (paddles @ 50 rpm) in 900 ml of 0.1N HCl at 37° C.:                not more than 40% of the total active is released at 2 hour;        from about 40-65% of the total active is released at 4 hour;        from about 60-85% of the total active is released at 8 hour.        